A coupling of this type is a modification of the known disc coupling which includes coupling halves that are developed as flanges and are connected to each other by bolts or similar connecting elements. In a disc clutch, the transmission of torque is effected solely by frictional engagement, with tensile stressing of the connecting bolts. With such a clutch, there are limits as to the torque which can be transmitted, when in the event of constricted space, the flanges cannot be developed as large as desired.
Accordingly, various measures have become known, which are directed at increasing the torque that a coupling can transmit without having to increase the outside dimensions of the coupling. Such measures comprise, for instance, the use of fitted bolts, the provision of radial toothing (see West German Patent 440 816 and West German Offenlegungschrift No. 25 54 574) or the insertion of a cotter between the end surfaces of the coupling halves. By such measures, the frictional drive for the coupling is supplemented or replaced by a positive drive. However, these known measures have the drawbacks that they cause high manufacturing expenses and/or the couplings are very sensitive to impact stresses.
Particularly in the known coupling with a cotter that has a rectangular cross-section, it is very expensive to insert the cotter with a snug fit into the cotter receiving grooves of the coupling halves. Even if a snug fit is obtained, the cotter in all cases rests only against a single side surface of each groove during the transmission of torque. There is a danger that the cotter will move laterally in the groove upon each change in the direction of the torque. This may lead to wear, particularly when torsional oscillations are present. In order to overcome this problem, the bolts must be so dimensioned that the coupling halves are also held together by friction, as in the case of a simple disc coupling, i.e. the bolt tensile force must be at least approximately as great as if the cotter were not present.
Theoretically, the side surfaces of the cotter and of the grooves could be inclined with respect to each other so that the cross-sections of the grooves are trapezoidal and the cross-section of the cotter is accordingly hexagonal. Although in this way, the cotter would rest snugly against the side surfaces of the groove, the end surface of one coupling half would no longer rest snugly against the end surface of the other coupling half. Thus, there would be a danger that the two coupling halves would no longer be in exact alignment.
In another known coupling shown in West German Auslegeschrift No. 1 450 160, an attempt has been made to solve the foregoing problem by developing a plurality of cotters, each in the form of a conically shaped pin. However, this manner of construction requires special measure for fastening of the conical pins, which would result in the danger described above. This known manner of construction is thus too expensive for many cases of use.